$x=10\cos\left(\pi t+\dfrac{\pi}{4}\right)cm$ 

a,

$v_{CB}=v_{\max}=A\omega=10\pi(cm/s)$

$a_{CB}=a_{\min}=0$

b,

$v_{\text{biên}}=v_{\min}=0$

$a_{\text{biên}}=a_{\max}=A\omega^2=10\pi^2\approx 100(cm/s^2)$

c,

$v=x'=-10\pi\sin\left(\pi t+\dfrac{\pi}{4}\right)$

$a=v'=-10\pi^2\cos\left(\pi t+\dfrac{\pi}{4}\right)$

Tại $t=0s$:

$x_o=10\cos\dfrac{\pi}{4}=5\sqrt2(cm)$

$v_o=-10\pi.\sin\dfrac{\pi}{4}=-5\pi\sqrt2(cm/s)$

$a_o=-10\pi^2\cos\dfrac{\pi}{4}\approx -50\sqrt2(cm/s^2)$ 

d,

Tại $t=\dfrac{1}{2}s$:

$x=10\cos\left(\pi.\dfrac{1}{2}+\dfrac{\pi}{4}\right)= -5\sqrt2(cm)$

$v=-10\pi\sin\left( \pi.\dfrac{1}{2}+\dfrac{\pi}{4}\right)= -5\pi\sqrt2(cm/s)$

$a=-10\pi^2\cos\left( \pi.\dfrac{1}{2}+\dfrac{\pi}{4}\right)\approx 50\sqrt2(cm/s^2)$

Đáp án:

 

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